Scientists have discovered a SECOND galaxy that contains little or no dark matter, adding further support for the existence of the baffling phenomenon

  • Researchers have found the second-ever galaxy without dark matter
  • The finding represents a shift in the way galaxies were thought to have formed
  • The galaxies also mark a step towards verifying dark matter’s existence  
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Dark matter is the most mysterious and prolific substance known to humans, accounting for a major portion of all matter in the universe.

That is, except for in two outlier subjects recently identified by researchers who say a dark matter-less galaxy found last year now officially has a companion.

The findings, published by Yale researchers, build upon research made public last year that for the first time showed evidence of a galaxy devoid of most, if not all, of the dark matter characterized in every other known galaxy across the universe.

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A previously discovered dark matter-less galaxy caused a wave throughout the astronomical community after being announced last year.

The team published the latest findings in The Astrophysical Journal Letters.

‘We thought that every galaxy had dark matter and that dark matter is how a galaxy begins,’ said Pieter van Dokkum of Yale University in a statement regarding the discovery last year. 

‘This invisible, mysterious substance is the most dominant aspect of any galaxy. So finding a galaxy without it is unexpected. 

‘It challenges the standard ideas of how we think galaxies work, and it shows that dark matter is real: it has its own separate existence apart from other components of galaxies…’

Similar to the first galaxy, a newly discovered dark matter-less twin, dubbed DF4, is also what researchers call an ‘ultra-diffuse’ galaxy, meaning they contain about 100 to 1000 times fewer stars than our own galaxy.   

‘The fact that we’re seeing something that’s just completely new is what’s so fascinating,’ said Professor of Astronomy at Harvard University, Shany Danieli, who first spotted the galaxy about two years ago.

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‘No one knew that such galaxies existed, and the best thing in the world for an astronomy student is to discover an object, whether it’s a planet, a star, or a galaxy, that no one knew about or even thought about.’

The discovery of both galaxies not only represents a surprising and unprecedented trend but cuts the core of a debate over the existence of dark matter itself — in this case, the discovery represents a major case in the affirmative. 

Dark matter is still unexplained. Some scientists think that the particles are too small to be observed. 

According to scientists, one of the biggest indications of the existence of dark matter — which has never been empirically observed — is that objects in the outskirts of our galaxy move at a much faster rate than they should given the levels of observable, normal matter.

Dark matter, scientists hypothesize, accounts for the fact that objects on the outer rim of the galaxy move faster than the mass of normal matter dictates. 

In the newly discovered galaxies, however, researchers note that the objects are moving at a speed consistent with the mass of normal matter. 

‘Ironically, the lack of dark matter in these UDGs strengthens the dark matter theory. 

It proves that dark matter is a substance that is not coupled to ‘normal’ matter, as both can be found separately,’ said researchers in a statement. 

From here, the teams says they will continue to look for other such galaxies to help strengthen their understanding of the phenomenon and maybe even unlock some clues to one of the universe’s darkest secrets.     

‘Our hope is that this will take us one step further in understanding one of the biggest mysteries in our universe – the nature of dark,’ said Danieli.


Dark matter is a hypothetical substance said to make up roughly 27 per cent of the universe.

The enigmatic material is invisible because it does not reflect light, and has never been directly observed by scientists.

Astronomers know it to be out there because of its gravitational effects on known matter.

The European Space Agency says: ‘Shine a torch in a completely dark room, and you will see only what the torch illuminates.

Dark matter is a hypothetical substance said to make up roughly 27 per cent of the universe. It is thought to be the gravitational ‘glue’ that holds the galaxies together (artist’s impression)

‘That does not mean that the room around you does not exist.

‘Similarly we know dark matter exists but have never observed it directly.’

The material is thought to be the gravitational ‘glue’ that holds the galaxies together.

Calculations show that many galaxies would be torn apart instead of rotating if they weren’t held together by a large amount of dark matter.

Just five per cent the observable universe consists of known matter such as atoms and subatomic particles.


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